Selective attention is a neurobiological process that allows animals to prioritize behaviorally relevant stimuli for perception. Humans, non-human primates and other vertebrates engage attention voluntarily to enhance perception of attended stimulus features in visual, auditory and tactile systems. Selective attention lowers perceptual thresholds for attended stimuli and enhances signal-to-noise ratio for neural coding of those stimuli. The local brain circuits that mediate selective attention are not well understood. One applicant mechanism is top-down gated disinhibition in sensory cortex, which boosts sensory responses to attended sensory features in pyramidal cells (PYR), thus prioritizing their processing. Vasoactive intestinal polypeptide (VIP) interneuron circuits have been suggested to mediate this disinhibition but have so far been implicated only in general arousal, not selective attention. We will measure neural activity of PYR and VIP neurons in somatosensory cortex (S1) of behaving mice performing an attention task, to determine whether cued attention enhances S1 sensory representations, and whether this involves activation of VIP cells. We will separately test whether top-down cues can drive temporal focus of attention (?attend now?) and spatial focus of attention (?attend here?). These experiments will allow us to determine if VIP cell circuits are involved in endogenous top-down attention, and to define the spatial precision of VIP circuit activation, which is currently unknown. Subsequent work will causally test the role of VIP circuits in selective attention, identify long-range inputs to VIP cells, and determine the local circuits downstream of VIP cells that drive attentional effects.